1. Field of the Invention
The present invention relates to an integrated active satellite antenna module, and more particularly to resolve the mutual coupling effect between the weak satellite signal and the other frequency channels of the integrated active satellite antenna module by means of the design rule of the RF front end circuit
2. Description of Related Art
Electromagnetic waves were extensively used to the radio communication in the 19th century after the electromagnetic wave was discovered by Maxwell in 1864. An antenna is an interface for the radio transmission and reception. The transmitting antenna delivers an electromagnetic wave and the receiving antenna transforms the energy of the electromagnetic wave into a current to be processed by a receiving circuit. Hence, the antenna has to tune to the correct frequency to eliminate noise and amplify the weak signal.
The key of a receiving antenna design is to receive the electromagnetic signal efficiency and isolate the noise from any other sources around the antenna effectively. Hence, how to prevent the mutual coupling effect to influence the normal function of the individual antennas in an integrated multiple antenna unit is the most important task.
Reference is made to FIG. 1, which is a functional block diagram of an integrated active satellite antenna module of the prior art, including a first input end 1a for importing a passive antenna signal, a low noise amplifier 4a for amplifying the band signal, a low loss filter 3a for filtering a noise and a band signal of the passive antenna, and a second input end 2a for importing an active antenna signal. Moreover, a switch 5a receives the passive antenna signal filtered and the active antenna signal for switching the signal source. The antenna signal is demodulated via the chip 6a and the output end 7a for exporting the antenna signal demodulated.
To sum up, there are some following disadvantages of the prior art:
(1) There is a serious mutual coupling effect between the particular antennas embedded in a small place.
(2) A satellite signal can't be demodulated via the RF chipset due to the operating power of the other antennas is too high to be processed by the front end amplifier when the other antennas are working.